Their tank is unkillable, someone build armor penetration.

What it actually means

"Pen" is short for penetration. "Tanky" is the adjective built from the noun: durable. A frontline that survives everything almost always means nobody bought penetration.

Related lines

• buy grievous wounds they healThey have healing, someone buy grievous wounds.
• build armor all adBuild armor, their whole team is AD.